Rex says
The fast lane for the math you almost remember from school. Type the numbers, get the answer, move on with your day.
Try a scenario
Click to load — tweak from there.Inputs
Water = 4186
Result
Energy (kJ)
1255.80
Energy (J)
1255800
Energy (kWh)
0.3488
Energy (BTU)
1190.3
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter mass (kg).
- 2Enter specific heat (J/kg·K) — Water = 4186.
- 3Enter temperature change (K).
- 4Read your energy (kj) on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Heating water, sizing a boiler, or checking how much energy a temperature swing costs — all the same equation.
Worked example
Using the values the calculator loads with:
Inputs
- Mass: 10 kg
- Specific heat: 4186 J/kg·K
- Temperature change: 30 K
Results
- Energy (kJ): 1,255.8
- Energy (J): 1,255,800
- Energy (kWh): 0.3488
- Energy (BTU): 1,190.3
What each field means
Inputs
- Mass (kg)
- The mass used in the calculation, measured in kg. Starts at 10 kg so you have a working example on load.
- Specific heat (J/kg·K)
- Water = 4186
- Temperature change (K)
- The temperature change used in the calculation, measured in K. Starts at 30 K so you have a working example on load.
Results
- Energy (kJ)
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Energy (J)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Energy (kWh)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Energy (BTU)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the heat energy (q = mcδt) calculator work?
Heating water, sizing a boiler, or checking how much energy a temperature swing costs — all the same equation. The underlying maths is: Q = m × c × ΔT
What do I need to enter?
3 values: mass, specific heat, and temperature change. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the energy (kj) result mean?
It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Results are rounded for display; the underlying calculation keeps full precision.
Who is this tool for?
It's built for students, developers, and anyone who needs the answer right now without setting up a spreadsheet.
Accuracy and limitations
- Results are rounded for display; the underlying calculation keeps full precision.
- Very large or very small inputs may hit floating-point limits in the browser.
- Inputs outside the accepted range are clamped rather than rejected.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Specific Heat Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/specific-heat
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/specific-heat" target="_blank" rel="noopener">Specific Heat Calculator — RevenueLab</a> (2026).</p>
Source: [Specific Heat Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/specific-heat) (2026).